Adobe Flash Media Server

Transcription

1 Technical White Paper Adobe Flash Media Server Transitioning from Microsoft Windows Media to the Adobe Flash Platform Table of contents 1 Key differences between Windows Media and Flash 2 Media distribution workflows 3 Experience design 3 Interactive programming 4 Live video broadcast 5 Media production 5 Digital rights management 6 Playback: Desktop clients 7 Playback: Browser plug-ins 9 Streaming server technologies 10 Data transfer protocols 11 Media formats 12 Streaming server tasks 13 Advertising 14 Announcements and metadata 15 Authentication and access controls 16 Custom plug-ins 17 Geofiltering 17 Key events 19 Large-scale deployments 21 Live broadcast streaming 23 Quality of Service 25 Protocol rollover 25 Provisioning users 26 Publishing points: Broadcast 27 Publishing points: Video on demand 28 Server SDK and productivity tools 29 Server monitoring 30 Server-side playlists 30 Tracking 31 URLs 32 Video on demand delivery 32 For more information 34 Appendix A: Flash Media Server essentials 42 Appendix B: Quick reference comparison chart 43 Appendix C: Glossary of terms The Adobe Flash Media Server family of products is an industry-leading solution for streaming media. Because of its strength, flexibility, and ubiquity, the Adobe Flash Platform provides a complete system to deliver the most engaging media experiences across virtually all operating systems and screens. Adobe Flash Media Server 3.5 software, the streaming technology behind the platform, supports both broadcast (live) and on-demand delivery services. This white paper is intended to assist server administrators familiar with streaming from Microsoft Windows Media Services in the transition to the Flash platform. Getting started is easy, and there are many reasons to switch, especially if you are currently using Windows 2003 technologies. This paper discusses the unique qualities of the Flash platform and the differences you will encounter when delivering media via Flash Media Server. Key differences between Windows Media and Flash Flash offers significant benefits over Windows Media, most notably user experience, workflow, and overall reach of the playback client. Traditional Windows Media playback is confined to a desktop player or browser plug-in that offers little customization. While you can increase your ability to customize by using the Silverlight plug-in to deliver Windows Media streams, Flash offers more flexibility in creative expression, richer interactions, wider reach and faster adoption, and enables the authoring and playback of rich media on a wide variety of platforms and devices. One of the greatest barriers to viewing video online is codec and plug-in ubiquity. A viewer who wants to play a stream generally does not want to download additional software to do so. Flash provides the simplest and least intrusive playback experience. Adobe Flash Player software is currently installed on over 98% of Internet-connected PCs and a growing number of devices. Along with its true cross-platform compatibility, this makes Flash a logical solution for reaching the widest audience. Flash also supports industry-standard video and audio codecs and bitrates. For example the H.264 industry standard, including HD quality up to 1080p (vs. 720p for Silverlight). Windows Media offers four choices of player on four computing platforms: Windows Vista, Windows XP, Windows Millennium Edition, and Windows The player required depends on which version of the Windows Media codec and which operating system and version you re using, and which processor is in your playback machine. For Flash, no choice is required: Simply use the latest version of Flash Player, and all Flash codecs play properly.

2 Media distribution workflows Web video is in a state of evolution. Watching video online used to be a passive experience that involved downloading a file and playing it back in a desktop player if you had the right codec and software installed. Consumers are now demanding smooth and seamless playback experiences, rich interactivity, and no barriers between them and the content they want to watch. Flash has helped drive this evolution, providing the interactive environment and nonintrusive playback experience that consumers have come to expect. Because Flash was designed to be an interactive, flexible, and customizable environment first then built on robust video capabilities it is a natural solution to meet the growing demands of consumers. A reliable, streamlined workflow is essential in media production and distribution, no matter what platform you deploy. The Flash Platform provides an integrated suite of tools that provide you with all you need to craft and deliver world-class video, audio, and interactive media on air, on devices, and online. The following sections each of these key workflows, differentiating between the Microsoft and Adobe solutions and illustrating the major benefits that make the Flash experience successful. Key workflows Adobe Compare to Experience design Adobe Flash CS4 Professional Adobe Encore CS4 Adobe Dreamweaver CS4 Adobe Photoshop CS4 Adobe Illustrator CS4 Adobe Flex Microsoft Expression Studio 2 Expression Web Expression Blend Expression Design Expression Media Expression Encoder Visual Studio 2008 Standard Interactive programming MXML and ActionScript XAML, VBScript, C# and Ajax Live video broadcast Adobe Flash Media Live Encoder Expression Encoder and Windows Media Encoder Media production Adobe Premiere Pro CS4 Adobe After Effects CS4 Adobe OnLocation CS4 Windows Movie Maker Microsoft Expression Media Microsoft Expression Encoder Adobe Encore CS4 Adobe Media Encoder Digital rights management Adobe Flash Media Rights Management Server Microsoft PlayReady Server Microsoft DRM Platform Playback: Desktop Adobe AIR Windows Media Player clients Adobe Media Player Playback: Browser Adobe Flash Player Microsoft Silverlight plug-ins Playback: Mobile Adobe Flash Lite 3 Windows Media Player for Mobile devices Streaming server Adobe Flash Media Server 3.5 Windows Media Server 2008 technologies Data transfer protocols Adobe RTMP and HTTP Microsoft RTSP and HTTP Media formats Sorenson Spark, On2VP6, H.264, HE-AAC, MP3, Nellymoser, Speex VC-1, WMA 2

3 Experience design The user experience is very important to overall viewer satisfaction. If a playback interface is not intuitive or attractive, the content will suffer. Windows Media and Flash both provide tools for creating user interfaces and scripting interaction. Microsoft Expression Studio 2 Expression Studio 2 is Microsoft s newest design and application package, combining its web and desktop design software into a single package. The five elements that make up the Studio suite are Expression Web 2, Expression Blend 2, Expression Design 2, Expression Media 2, and Expression Encoder 2. To assist legacy programmers, Expression Studio 2 also includes a standard edition of Visual Studio 2008 for custom experience design. Design 2, a tool similar to Adobe Photoshop Elements or ImageReady software, can export artwork to other products including XAML and bitmap files. It can also create slices in a range of file formats. Adobe Creative Suite 4 Adobe Creative Suite 4 software features components that provide a complete, integrated workflow, creating rich interactive experiences on the Flash platform. Specific tools for experience design include: Flash CS4 Professional Authoring environment for creating rich interactive multimedia experiences. Photoshop CS4 Extended Digital imaging software with new features for working with 3D imagery, motion content, and advanced image analysis. Illustrator CS4 Authoring environment for creating vector graphics. Encore CS4 A set of creative tools for DVD and Blu-ray Disc authoring as well as SWF file export to the web. For more details, see Flex 3 A free open-source framework for building and maintaining web applications for deployment in Flash Player. Adobe Flex Builder 3 software can be used to author Flex applications. Interactive programming Both Windows and Flash platforms have tools for creating interactive experiences, but the scripting languages and their capabilities differ. XAML and VBScript Expression Blend 2 is the tool most akin to Flash in terms of creating and modifying Silverlight-based websites. Blend 2 doesn t yet support Silverlight 2, but it has design features such as a split design/xaml view. Due to the necessity of using Visual Studio 2008 to do the heavy programming lifting, programmers must work either in Visual C# language or Visual Basic and target.net Framework v3.5 or v3.0. Users comfortable with programming in a desktop environment use Visual C# as the core programming language. Users experienced with web-based development will be more comfortable in.net. In either case, users would need training to make the move to including XAML for web-specific programming. MXML and ActionScript You can use two languages to create SWF files for the Flash platform: MXML and ActionScript. The Adobe SWF format is an open, license-free specification. ActionScript is the programming language used in the Adobe Flash Player runtime. Originally developed as a way for Flash developers to program interactivity, ActionScript enables efficient programming of Flash applications for everything from simple animations to complex, data-rich, interactive application interfaces. 3

4 ActionScript 3.0, introduced in Flash Player 9, is based on ECMAScript the same standard that is the basis for JavaScript and provides incredible gains in runtime performance and developer productivity. ActionScript 2.0, the version of ActionScript used in Flash Player 8 and earlier, added language constructs and features to enable developers to build large-scale, object-oriented Flash applications and content. ActionScript 2.0 continues to be supported in Flash Player 9. MXML is an XML markup language used to lay out user interface elements in Flex applications, which are also deployed as SWF files on the Flash platform. Flex is a highly productive, free and open source framework for building and maintaining web applications that deploy consistently on all major browsers, desktops, and operating systems. It provides a modern, standards-based language and programming model that supports common design patterns suitable for developers from many backgrounds. Flex applications run in the ubiquitous Adobe Flash Player and Adobe AIR runtimes. ActionScript is used with MXML to create SWF files. Because MXML files are ordinary XML files, you have a wide choice of development environments. You can write MXML code in a simple text editor, a dedicated XML editor, or an integrated development environment (IDE) that supports text editing. Adobe supplies a dedicated IDE, Flex Builder built on the open source Eclipse platform, that you can use to develop your applications. Flex Builder features a prebuilt Flex component set and powerful debugging tools. You can use a text editor or other third party IDE to write AS files and then use the free and open source Flex SDK to compile to SWF. Live video broadcast Live video broadcast is a feature of both Windows Media and Flash Media Server platforms. Both have tools for live encoding but differ in their playback and deployment complexity. Expression Encoder and Windows Media Encoder Expression Encoder, a feature of Expression Media, supports live and on-demand encoding and template-based publishing of Silverlight media experiences. In addition, Silverlight works with a broad range of Windows Media encoding tools and utilities available today. Windows Media Encoder is another option for broadcasting live video. To make this live feed web accessible, however, you must embed a player in a web page that your viewers access through Internet Explorer (version 4 or later) with Windows Media Player installed, or provide a URL to play back in the standalone Windows Media Player application. Adobe Flash Media Live Encoder Adobe Flash Media Live Encoder is a free software application that allows you to quickly and easily capture live audio and video while streaming it in real time to Flash Media Server software or Flash Video Streaming Service. With an intuitive user interface that works efficiently with both consumer and professional plug-and-play cameras and microphones, and compatible analog-to-digital converters, Flash Media Live Encoder features support for On2 VP6 and H.264 video codecs and Nellymoser, the open source Speex codec, or MP3 audio codecs (AAC available with separate plug-in). Other features include: Local archives of streams Metadata injection Auto-restart after power interruptions Auto-adjust to network conditions Multipoint publishing point Multiple bit rate support Support for DVR functionality Flash Media Live Encoder can also be run from a command-line interface (CLI), making it possible to set up continuously running encoding sessions and to integrate them with existing automated systems. 4

5 Media production A streamlined media production workflow is essential to deploying web video. While Microsoft provides some media production tools, Adobe has a well-established and robust suite of software available. Windows Movie Maker, Microsoft Expression Media, and Microsoft Expression Encoder Windows Movie Maker 2 is a free tool bundled with Windows XP and and Windows Vista that is capable of basic cuts and a few transitions, with limited captioning and output formats. To overcome the limitations of Windows Movie Maker, Microsoft promotes Expression Studio. One of Studio s tools is Expression Encoder. The newest version, Encoder 2, optimizes many types of video for web playback, as well as basic segment deletion/editing. Because Windows Movie Maker does not support VC-1, Expression Studio 2 is the only way to get the new VC-1 codecs. Adobe Premiere Pro, Adobe After Effects, and Adobe Media Encoder Adobe s media production workflow consists of Adobe Premiere Pro and After Effects software for editing, Adobe OnLocation for camera calibration and direct-to-disk recording, and Adobe Encore for DVD and Blu-ray Disc authoring. Adobe Premiere Pro is professional editing software, providing an efficient tapeless workflow, real-time rendering, metadata support, and advanced editing tools. It can encode media in a wide range of major video, audio, and graphic file formats, including FLV, F4V, MPEG-2, QuickTime, Windows Media, AVI, BWF, AIFF, JPEG, PNG, PSD, TIFF, and others, and it exports Flash compatible codecs (H.264, On2 VP6). After Effects is an industry standard for motion graphics and visual effects and also supports Flash compatible file formats and codecs. Adobe s standalone encoding software, Adobe Media Encoder, ships with Flash CS4 Professional and features batch processing, H.264, and On2 VP6 encoding and fine control over encoding settings. Digital rights management Digital rights management (DRM) is a notorious moving target, with encryption schemes of the past being compromised almost as quickly as they are released. Still, content integrity is vitally important to content owners, so robust DRM protection has been developed for Windows and Flash Media Server platforms to protect both streaming and downloaded content. Microsoft PlayReady Server and Microsoft DRM Platform The Microsoft DRM Platform (Windows Media Rights Manager) consists of several key elements as a way to package the digital media file for secure delivery and playback. The license key is stored in a separate encrypted file, which is distributed separately. The URL where the license can be acquired is sent along with the digital media file (either a Windows Media Audio file with a.wma filename extension or a Windows Media Video file with a.wmv filename extension. A license server must be established, typically through a license clearinghouse that implements the Windows Media Rights Manager License Service and authenticates consumer requests for a license. As mentioned previously, digital media files and licenses are distributed and stored separately, making it easier to manage the entire system. A consumer must first acquire a license key to unlock the file, prior to playing the file or stream. Automated license acquisition occurs when the consumer attempts to play the file for the first time, which requires two steps: acquiring the packaged digital media file (or stream) and acquiring a predelivered license. Alternatively, Windows Media Rights Manager can send the consumer to a registration page where information is requested or payment is required, prior to playing. Licenses can have different rights, such as start times and dates, duration, and counted operations, but the player must support Windows Media DRM. Licenses are not transferable, meaning other viewers on their own machines must acquire their own license to play the digital media file. 5

6 Consumer electronics devices must have applicable compliance rules and must be designed and manufactured so as to resist attempts to modify such PlayReady Final Products so as to defeat the functions of the Microsoft Implementation, meaning that they can t include switches, jumpers, or traces that may be cut, or control functions means (such as end-user remote control functions or keyboard, command, or keystroke bypass) to bypass the PlayReady DRM. This includes devices that resist attempts to discover, reveal, and/or use without authority the Device Secrets; and/or discover or reveal the Content Keys, License Integrity Keys, and/or Intermediate Keys or Confidential User Information. Adobe Flash Media Rights Management Server In addition to the built-in protection of encrypted RTMP (RTMPE) delivery and SWF file verification featured in Flash Media Server 3.5, Adobe has introduced an additional content protection tool for both streaming and progressive delivery Adobe Flash Media Rights Management Server software. Flash Media Rights Management Server lets content owners and distributors control how and where their content can be distributed and experienced, even after it has been downloaded. It encrypts FLV/F4V files that are downloaded onto a Mac and/or Windows platform and sets policies for their access. Unlike most content protection solutions available today, Flash Media Rights Management Server is not limited to certain platforms or devices. Its two client options Adobe Media Player and Adobe AIR allow users to download media content to either their Mac or Windows systems and play it back whether they are online or offline. Flash Media Rights Management Server can tightly associate content with branding and advertisements, or it can allow digital assets to be licensed to users or groups of users. Another option is a custom application developed on the Adobe AIR platform that incorporates downloaded video as part of a rich Internet media experience. Flash Media Rights Management Server software consists of three major components: Rights Manager, Media Packager, and Adobe Media Orchestration Documents (AMOD) Signer. Administrators access these three tools via Java based CLIs. In addition, Flash Media Rights Management Server contains a service provider interface (SPI) that lets content owners leverage existing user authentication and authorization mechanisms. For more details, see Playback: Desktop clients You can use two playback methods for streaming video content: a browser plug-in or a standalone application on the desktop. Windows Media Player Windows Media Player is the standalone desktop application that plays Windows Media streams. It supports progressive downloading and includes a Fast Start feature introduced in Windows Media 9 that allows on-demand video streams to start quickly without significant buffering and caches content on the local hard drive to play back from a buffer. Windows Media Player is a simple player, without custom interactivity. Windows Media streaming was one of the earliest streaming technologies on the market. Introduced over a decade ago, Windows Media Player is capable of streaming live content while simultaneously archiving a local copy of the stream for later playback. Microsoft originally used a proprietary protocol called Microsoft Media Server. Sitting atop Windows Media Services, the protocol was used for unicast streams transported via UDP or TCP. While Microsoft Media Server has been around for about a decade, Microsoft dropped support for it in the 2008 version of Windows Media Services. This means that all users, including corporate users that use the older Windows Media 7 video codec for compatibility with older computers, must either upgrade to 6

7 Windows Media Player 9 or continue to use the older 2003 version of Windows Media Services. Because Microsoft also discontinued support for the Macintosh version of Windows Media Player, Mac users must use Flip4Mac, a third-party desktop player developed by Telestream. (See the chart in the Key differences between Windows Media and Flash section for specific requirements.) Adobe AIR Adobe AIR is a cross-operating system runtime that lets developers combine HTML, Ajax, Flash, and Flex technologies to deploy rich Internet applications (RIAs) on the desktop. With Adobe AIR, developers can use familiar tools such as Adobe Dreamweaver CS4, Flex Builder 3, Flash CS4 Professional, or any text editor to build applications and deliver a single application installer that works across operating systems. Adobe AIR is available for Microsoft Windows 2000; Windows XP; Windows Vista Home Premium, Business, Ultimate, or Enterprise; Linux; and Mac OS X v10.4 or Adobe AIR can be used to create completely customized Flash based desktop media players that are, unlike Windows Media Player, fully cross-platform. Adobe Media Player If you have a large catalog of content and you d like to monetize it and broaden your reach, you may want to consider Adobe Media Player as a distribution channel. Adobe Media Player is a free cross-platform desktop application built by Adobe on Adobe AIR and specifically designed to play back streamed or downloaded FLV or MPEG-4 video content when users are online or offline. With Adobe Media Player, users can discover, organize, and subscribe to video content and even automatically download subscribed episodes. The customizable, cross-platform player leverages existing Flash technology and supports downloaded and streamed media of up to full-screen HD resolution. With Adobe Media Player, you can customize brand experience and measure usage and ad results whether viewers watch online or offline. You can place advertising in or around your content with dynamically delivered banners, in-rolls, or bugs. You can also customize the backgrounds and logos that display around your video. These dynamic elements follow your video streaming or downloaded, online or offline. All of these elements, including your content, are fed into Adobe Media Player via a simple RSS file. Adobe Media Player runs on both Windows and Mac operating systems. For more details, visit Playback: Browser plug-ins Playing streaming video in a browser often requires a plug-in. While Windows Media Player can be embedded in a browser via JavaScript, Microsoft encourages the use of the Silverlight plug-in for cross-platform compatibility. Flash uses Flash Player. Flash currently has significant advantages, including a far wider install base, compatibility across platforms and a wide range of devices, and rich interactivity. 7

8 Microsoft Silverlight Microsoft Silverlight is a new cross-browser, and cross-platform plug-in for delivering media experiences and rich interactive applications for the web. Silverlight supports.net scripting, video quality up to high definition (max 720p), streaming or progressive playback, and interactivity. The latest release, Silverlight 2, includes a set of built-in controls, representing a subset of the.net framework, that developers and designers can use to build basic applications. Silverlight supports all major browsers on both Mac OS (Intel only) and Windows. (See Appendix B for specific requirements.) Silverlight will support Linux with a third-party version of the plug-in, produced through a partnership with Novell. Silverlight supports Windows Media Audio and Video (WMA, VC-1/WMV7 9) video codecs as well as MP3 audio. Silverlight s adoption rate is in the area of 25% in comparison to the ubiquity of Flash Player at 98%. It will likely be some time before Silverlight can achieve the browser penetration of Flash player. Adobe Flash Player Adobe Flash Player is the current standard cross-browser, cross-platform, and cross-device plug-in for delivering Web applications, interactive content and rich media experiences for the web. Over 86% of online videos in the United States are viewed using Flash technology, according to the September 2008 report released by the independent research firm comscore, making it the number one way to view video on the web. Flash Player has featured support for on-demand and live streaming video since version 6. Flash Player 9 and above supports high-definition video quality, streaming or progressive playback, and rich interactivity. Flash Player deploys applications as SWF files, based on the open SWF file format. Developers can use Flash CS4 Professional, Flex Builder 3 or the free and open source Flex SDK to build SWF files for Flash Player, writing them in ActionScript, which is based on ECMAScript. Both Flash and Flex contain prebuilt components to rapidly build applications for deployment in Flash Player or Adobe AIR. Adobe AIR supports all formats. Media formats supported on the Flash platform include: Type Container Flash Player minimum Usual pairing Sorenson Spark Video FLV 6, 7, 8, 9+ Nellymoser/MP3 On2 VP6 Video FLV 8, 9+ Nellymoser/MP4 Flash Lite 3 H.264 * Video MPEG-4: MP4, M4V, F4V, 3GPP 9,0,115,0+ AAC+/MP3 Nellymoser Audio FLV 6+ Spark/On2 Speex Audio F4v 10 Sorensen MP3 Audio MP3 6+ Flash Lite 3 AAC+/HE-AAC/AAC v1/ AAC v2 Audio MPEG-4: MP4, M4A, F4V, 3GPP Spark/On2 9,0,115,0+ H.264 For more information on H.264/AAC support, see the Flash Player 9 Update FAQ at For further exploration of browser versus desktop deployment, see the comparison matrix at * H.264 playback in Flash Player supports most popular profiles including Base, Main, and High. The F4V format is a new format that is a subset of MPEG-4 (ISO ) and AAC+ (ISO ). 8

9 Streaming server technologies Both Windows and Flash platforms have their own proprietary server technologies, with varying complexity in setup and deployment. Windows Media Server 2008 Windows Media Server 2003 shipped with everything needed for streaming in one package. Windows Media Server 2008 is configured using modules that allow you to selectively turn features on and off. While this does improve the efficiency of the server, it also provides an additional level of complexity to deployment. Adobe Flash Media Server 3.5 Flash Media Server is the underlying platform for the vast majority of streaming and multiway experiences that use Flash technology on the web today. With Flash Media Server s extensible development architecture, you can deliver enhanced multiway communications, DVR functionality, secure HD-quality video, integrated live video streams, delivery to mobile handsets and devices, and deep interactivity. Because of Flash Media Server s sophisticated firewall, proxy transversal, and player integration with your website, viewers can reliably access media content with instant-on playback. Key features of Adobe Flash Media Server include: Improved H.264 performance. Deliver more streams using fewer server resources. Dynamic Streaming. Deliver live or on-demand video at the best quality as network conditions change. Integrated HTTP server. Help ensure that your content is easily and reliably delivered, even when RTMP delivery is not supported. XMP metadata support. Full support for streaming XMP metadata created by video production tools that write it into the file. DVR functionality. Pause and seek within live video. New productivity tools. Suite of productivity tools to assist in managing your media, delivering optimized streams, and evaluating server health. Support for encrypted media delivery. Supports integration with Flash Media Rights Management Server for delivery of signed and encrypted media to desktop applications running on AIR, including Adobe Media Player. More secure content delivery. Adobe s Real Time Messaging Protocol (RTMP) is enhanced with new, higher performance, 128-bit encryption (RTMPE) to help protect streamed media and communication. HD video and high-quality audio. Support for streaming industry-standard H.264 and HE-AAC video and audio content. Server-side plug-in architecture. Supports plug-ins written in C++ that you can customize to extend the server s functionality Multipoint publish. Control your feed out to a content delivery network (CDN), which would then broadcast it to your viewers. Connection throttling. Connection-handling management that promotes high quality of service for connected viewers. IPv6 support. Required by many government customers, Internet Protocol Version 6 (IPv6) is the next-generation protocol, replacing IPv4 (that is, ). Administration API. Create custom tools to monitor, configure, and manage Flash Media Server. 9

10 Enhanced process scopes. Flexible configuration of server process scopes to optimize server performance. Prebuilt services. Flash Media Server ships with special prebuilt services and sample files that make it easy to stream right out of the box. Data transfer protocols Windows Media and Flash Media Server use different protocols to deliver content. Both can support HTTP delivery when needed. Microsoft RTSP Real Time Streaming Protocol (RTSP) is an open standard transmission protocol, adapted by many servers, including Windows Media, QuickTime, and Helix. The base protocol of RTSP, like RTMP, is based on the Real Time Transmission Protocol (RTP). RTSP streaming, at the outset, requires verification between client and server before sending a stream. Windows Media Player versions 9 through 11 attempt to connect first with RTSP over UDP. If that fails, it attempts RTSP over TCP. One capability that Windows Media supports that Silverlight and Flash do not is multicasting. A multicast stream is one that is broadcast to many users at the same time, rather than point to point (unicast). A multicast stream allows many people to watch a single data stream, potentially reducing server resources and bandwidth. However, most routers are not multicast enabled, so this solution is limited to specialized enterprise deployments. Adobe RTMP RTMP, by comparison, uses TCP, which is considered a reliable transmission. How does a reliable transmission avoid delays and requests for retransmissions during real-time streaming? The RTMP transmission protocol always transmits a mixed stream of video, audio, and data packets. As the quantity of video packets is greater than that of audio packets, this allows the end user to avoid spending more time waiting to receive the audio packets if they arrive after the video packet, as well as guarantees that video and audio are synchronized. Flash Media Server supports a number of configurations of RTMP: RTMP: This is the standard, unencrypted Real-Time Messaging Protocol. RTMPT: This protocol is RTMP tunneled over HTTP; this means that the RTMP data is encapsulated as valid HTTP data. RTMPS: This protocol is RTMP sent over a Secure Sockets Layer (SSL). SSL is a protocol that enables secure TCP/IP connections. (Flash Media Server natively supports both incoming and outgoing SSL connections.) RTMPE: This protocol is an enhanced and encrypted version of RTMP. RTMPE is faster than SSL and does not require certificate management as SSL does (supported with Flash Player 9,0,115,0 and later; Adobe AIR; Adobe Media Player). The key benefits over SSL (RTMPS) are performance, ease of implementation, and limited impact on server capacity. RTMPTE: This protocol is RTMPE tunneled over HTTP (supported with Flash Player 9,0,115,0 and later; Adobe AIR; Adobe Media Player). HTTP HTTP delivery can be used by both Windows Media and Flash Media Server if their native protocols are not available. Microsoft now supports RTSP as a standard protocol, and its Windows Media Services 2008, using Windows Media Server 2008, also supports the HTTP protocol and the H.264 video codec (excludes Silverlight). 10

11 Flash supports RTMP as a standard protocol for streaming from Flash Media Server. However, if for some reason RTMP is not available for a certain client, Flash Media Server 3.5 can detect this and roll over to HTTP delivery through its built-in Apache server. This server can also be used to deliver the nonstreaming elements of a media application if desired. Media formats A codec is not the same thing as format. Since audio or video only requires encoding to be able to be transmitted across limited data pipes (such as consumer DSL or cable modem), a codec is only required in certain situations. A format, however, is always required, as it is the container in which the compressed or uncompressed audio and video reside. On the audio side, everyone is familiar with the MP3 container format, which is based on MPEG-2 Part 2 audio. The beauty of MP3 as a format is that, like FLV or WMV video formats, it can hold multiple codecs. For example, when you encode an MP3 file with the LAME codec, it is not LAME file, LAME format, but instead it is an encoded MP3 file that can be decoded with other MP3 decoders. This is the most important part of standards such as MPEG-2 or MPEG-4: any codec can be used to encode, but all decoders must comply with the standard, so that all decoders can decode the same content. Proprietary formats hold both the encoder and decoder as well as the format. For instance, for the proprietary Windows Media, the format is WMV for video or WMA for audio, while the codec is a Windows Media 9 Series audio or video codec, which must then be played in a Windows Media Player. VC-1 and WMA Microsoft has a variety of codecs, the most recent one being VC-1. This codec, which is based on the Windows Media 9 Series codec, was released to the Society of Motion Picture and Television Engineers (SMPTE) organization several years ago in hopes of it being adopted as a standard. It is Microsoft s only codec that is capable of being used for High Definition (max of 720p) content. Sorenson Spark, On2 VP6, H.264, MP3, Nellymoser, HE-AAC The video format for Flash is FLV, and the codec can be either On2 VP6 or Sorenson Spark, with the latter being the original FLV codec. Nellymoser is the audio codec that is generally paired with Sorenson Spark video, and MP3 is generally used for On2 VP6 video. With Flash Media Server streaming, Sorenson Spark/Nellymoser recording is supported by Flash Player, enabling user-generated content and archiving completely within the browser. On2 Technologies created VP6 (in both the Simplified and Enhanced versions) for use in a variety of low-latency products, including Instant Messaging (IM) video. It is a proprietary codec best known as Flash Video 8, the codec that gave Adobe dominance in web-based streaming and spawned the FLV format extension. The codec is agile and extensible, with the new Simplified version capable of encoding and decoding High Definition 720p content. H.264 is a standards-based (nonproprietary) codec that is a subset of the MPEG-4 format. H.264, known as both AVC and MPEG-4 Part 10, is similar enough to MPEG-2 that it can be transported as part of an MPEG-2 transport stream. This is important for enterprise and broadcasters that have invested in large-scale MPEG-2 transport distribution networks. Microsoft and Adobe have both embraced H.264, with Microsoft s IIS 7 server component supporting H.264 and a recent announcement that on-demand H.264 will be playable in a future release of Silverlight.. HE-AAC is an audio codec that goes hand in hand with H.264 video as part of the MPEG-4 open standard. The intent was to replace MP3, which is part of the MPEG-2 open standard and is therefore less efficient and more lossy than AAC at equivalent bitrates. An AAC file encoded at 11

12 64kbps is equivalent to a 256kbps MP3 file, and the new HE (High Efficiency) portion of AAC allows for even greater dynamic range, rendering HE-AAC as the codec closest to the sound of an uncompressed audio file. Streaming server tasks To assist in migration to Flash Media Server, this section reviews common streaming server tasks and how they are achieved on both the Windows Media and Flash Media Server platforms. Microsoft Windows Media Services Adobe Flash Media Server Advertising Announcement file ASX file Custom Silverlight player Server-side playlist XML or SMIL playlist Ad-serving service APIs Announcements and metadata ASX metafiles File locations: XML or other external data source Hard-coded or passed as variables at runtime Metadata: Read directly from media file XML or other external data source Hard-coded or passed as variables at runtime Authentication Windows NT LAN Manager (NTLM) HTTP basic authentication (via NTLM or REST) Active Directory Custom plug-in using MD5 hashed passwords Integration with Adobe ColdFusion or other server technology Server-side ActionScript Access adapter plug-in Authorization adapter plug-in Dynamic access control list Secure tokens via web services (SOAP), Flash Remoting, or XML Custom plug-ins Archiving Authentication Authorization Cache/proxy management Control protocol Data source Event notification Logging Multicast streaming Playlist/media parser Playlist transform Unicast streaming Custom plug-ins File Access remote file locations Remap files to physical locations Content management control Remote SWF file verification Authorization Control client access to server events Remap stream URLs Call server-side methods Geofiltering Subscription control Access client statistics QoS monitoring Access Intercept connection requests Control access criteria Set read and write access for file system Authentication and database access Geofiltering Filter by IP address Filter by IP address Key events DirectShow API, with JavaScript, Visual Basic, and procedural languages Large-scale deployments Multicasting Proxy caching Live broadcast streaming Windows Media Server 2003 Windows Media Server 2008 (with Windows Media Services 2008) CDN ActionScript event model, communication with JavaScript Origin-Edge configurations Multipoint publishing Flash Media Server 3.5 Flash Video Streaming Service 12

13 Microsoft Windows Media Services Adobe Flash Media Server Quality of Service Protocol rollover Publishing points (broadcast) Publishing points (video on demand) Server SDK and productivity tools Server monitoring Quality of Service policies to manage outgoing network traffic (Windows Media Services only) Adaptive streaming Windows Media Load Simulator RTMP to HTTP using the Server Control Protocol plug-in (legacy Windows Media Player versions) Unicast Announcement Wizard Multicast Announcement Wizard Manual addition of PP URL to distribution server Unicast Announcement Wizard Device management Windows Media Device Manager SDK Windows Media Encoder SDK Windows Media Services SDK Server-level monitoring (Windows Server 2008 with Windows Media Services) Dynamic Streaming (multibitrate) Native bandwidth detection Viewer statistics monitoring Origin/Edge configurations Load Simulator tool RTMP with port rollover (automatic: 1935, 443, 80), HTTP Live service Custom live application VOD service Custom VOD application Server Side ActionScript Administration Console Administration API FMSCheck tool FLVCheck tool Load Simulator tool F4V Post Processor tool Sample video player with Dynamic Streaming support Server-level monitoring on Linux or Windows Server installations Flash Media Server 3.5 Admin Console Server Check utility Administration API Server-side playlists External playlist files (ASX files) Server-side ActionScript (ASC files) SMIL/XML support Tracking Windows Media Server 2008 tracks completed and incomplete streams, length of time watched, IP address, and other viewing details (when authentication is used) Flash Media Server 3.5 features custom logging, allowing you to track virtually any metric required, including access information, application-level activity, and server diagnostics Video on demand delivery Web server (HTTP) Windows Media Services CDN Web server (HTTP) Flash Media Server 3.5 (RTMP) CDN Advertising Control over advertising is an increasingly vital part of many streaming media applications. If you ve ever created ad-supported content with Windows Media Services, you know that it requires a significant amount of preplanning, regardless of whether the ads are wrapper (often referred to a pre-roll or post-roll), interstitial, or banner. Windows Media Windows Media Player offers less flexibility than Flash Player to add banner ads, which is why Microsoft is now encouraging adoption of the Silverlight player. Windows Media Services uses two types of approaches for banner ad delivery: You can use either a banner URL in an announcement file (see Announcement and metadata for more detail) that leverages the BANNER metadata element or a bannerurl attribute in a server-side playlist file. This attribute, coupled with a clientdata element, is the best option, since the playlist is also needed for wrapper and interstitial ads. (For more detail on this topic, see Server-side playlists. ) 13

14 Flash Unlike Windows Media Services, which requires a playlist to use interstitial advertising, Flash custom players can have spaces built in to display banner ads, which don t require a significant amount of preplanning for ad insertion. Interstitial and pre- and post-roll video ads are also easier to implement, using simple SMIL files or custom XML playlists. These solutions can be implemented for progressive or streaming delivery, or a combination of both. Numerous ad-serving services assist in tracking and managing advertising in Flash applications. Announcements and metadata One of the foundations of the Windows Media deployment structure is the announcement file. Flash approaches metadata and deployment in a more flexible way. Windows Media Microsoft Windows Services uses an ASX file to create playlists (see Server-side playlists ) and to announce to the client player where to find the content. This is useful when content may be changing (such as during a live event or a large-scale on-demand playback). As mentioned in Protocol rollover, this announcement/asx file is also helpful for assessing various protocols to use for playback. Shifting protocols from mms:// to can be accomplished in an ASX file, as can an rollover to rtsp:// (port 554). In addition, dynamically generated ASX files can handle multiple servers serving up the same video content, where a rollover URL identifies alternate Windows Media servers that are streaming the same content. This ASX metafile directs the player to a particular Windows Media server to receive content, and the announcement file can be placed on a web page or ed. Microsoft notes that an announcement wizard in Windows Media Services creates announcement files and can even create a web page with an embedded Windows Media Player control. Flash Flash can use many different source formats to create playlists and announce to clients where to find content. XML is a standard way to define playlists and provide additional data about media files in addition to their locations. Using the ActionScript onmetadata event listener, you can even retrieve metadata that is encoded directly into the media file itself. Some common metadata contained in FLV or F4V files includes: Audio codec Audio datarate cuepoints duration framerate height videocodecid videodatarate width In Flash, metadata can be read from media at runtime via ActionScript. Some metadata, such as cue points, can be added dynamically and used for custom behaviors such as navigation or captioning. 14

15 Authentication and access controls Protection of your streaming content is an important feature in any server technology. Both Windows and Flash Media Server allow authentication, but Flash offers a wider variety of protection methods. Windows Media Windows Media Services, both 2003 and 2008, can be set up to authenticate usernames and passwords. Several options include the older Windows NT LAN Manager (NTLM) authentication and account database, the use of HTTP basic authentication (via either NTLM or REST), a custom plug-in, or via Active Directory. Because NTLM does not support delegation, its authentication of clients to remote content fails and the user is prompted repeatedly for credentials, even though valid credentials have been entered. As a result, Microsoft recommends moving toward HTTP authentication. To play Advanced Streaming Format (ASF) content from a publishing point, the viewer is required supply a user name and password. While this can be used for Internet environments and cross-platform authentication, it s best used for intranets since it sends clear-text, nonencrypted usernames and passwords across the network. without the use of any encryption. Newer solutions typically access a mysql or SQL Server database and use MD5 hashed passwords. Another option is URL referring, which means that requests to stream must come from a particular URL or the stream is not shown. Flash Several methods of user authentication are available with Flash Media Server 3.5. A user authentication scheme can be developed in ActionScript to validate the connecting client. For example, using variables passed to the server from the client, you could implement a simple username/password, an encrypted token (MD5 hash), or a unique key. Then, on the server side, Flash Media Server would be able to integrate with web services (SOAP), Flash Remoting, XML, HTTP post, or simple file access to validate the client based on the data sent. This authentication scheme could be as simple as checking login information against a database, or as sophisticated as creating an SSL-based token system using ColdFusion. Another option is to use an access adapter. An access plug-in is a server plug-in for Flash Media Server written in C++ that intercepts connections to the server and determines whether requests should be accepted, rejected, or redirected before the requests reach the server s script layer. You can create custom logic in the access adapter to handle client connection requests. For example, you could query your account database upon client login, and then update the database record after the client connection was accepted. The access plug-in can be configured to accept or reject requests based on the number of clients currently connected or the amount of bandwidth currently being consumed. You can also set read and write access for files and folders on the server, set permissions to access audio and video bitmap data, and inspect client properties through the access adapter. An authorization plug-in is another flexible authentication option available with Flash Media Server. With a server plug-in written in C++, the authorization adapter authorizes client access to server events. Authorization adapters can: Authorize connections to the server Authorize playing a stream or seeking in a stream Authorize publishing a stream Disconnect clients from the server Call a method in server-side ActionScript Deliver content to clients according to their geographic location, subscription level, and stream origin 15

16 Limit time and duration of a user s access to specific streams Map a logical stream path to a physical stream path; for example, a client requests the stream foo.flv, but since he or she is not a premium member of the service, he or she should only receive the low-quality version of that content, so the client is actually served bar.flv Access control is also possible using server-side ActionScript. You can create a dynamic access control list (ACL) that controls who has access to read, create, or update shared objects or streams. SWF file verification is yet another approach to authentication available with Flash Media Server. This feature allows you to compare the SWF file requesting the stream to an approved library of SWF files to be sure stream request is originating from an authentic source. Used in conjunction with stream encryption, this approach offers a high level of security for your content. Custom plug-ins Server plug-ins extend the functionality of the streaming server. Both Windows and Flash servers feature plug-in architecture. Windows Media Windows Media Services 2008 can be customized by plug-ins to the Windows Server 2008 architecture or to Windows Media Services 2008 itself. The list of plug-in modules that come with Windows Media Services 2008 includes: Archiving Authentication Authorization Cache/proxy management Control protocol Data source Event notification Logging Multicast streaming Playlist/media parser Playlist transform Unicast streaming Custom plug-ins using the Windows Media Services 9 Series Software Development Kit (SDK) Flash Most of the functionality of Flash Media Server is built in and configurable via XML files, but you can also extend functionality using the plug-in architecture written in C++. You can use these plug-ins to build unique Adobe Flash Media Interactive Server and Flash Media Development Server deployments with expanded access, authorization, and file management features. Three types of plug-ins are available: File Gives you control over where and how the server reads content from the file system. Can be used to grab files from remote locations over HTTP to offload content management duties, remap files to different physical locations, and retrieve external SWF files for SWF file verification security checks. Authorization Authorizes client access to server events such as connecting to the server, playing, publishing or seeking in a stream. Can also be used to remap stream URLs, disconnect clients from the server, call server-side ActionScript methods, deliver content to clients based on their geographic location or subscription level, or access client statistics. You can also use this plug-in to monitor stream quality of service (QoS). The plug-in reports live stream QoS information to an external log file, which can then be read. 16

17 Access Adds a layer of security to the server by intercepting connection requests, allowing you to examine the client to determine whether the request should be accepted. Can also be used to specify access criteria, such as how many users are currently connected and the amount of bandwidth being consumed, and set read and write access for files and folders. You can even query a database to authenticate the client and update the database with a record of the user s access to the server using this plug-in. For more details, refer to the Adobe Flash Media Interactive Server Plug-in Developer Guide. Geofiltering Geofiltering is an online equivalent of the arbitrary boundaries that have been used for cable, satellite, and terrestrial television broadcasts. Also referred to as georestriction. Some CDN services perform geofiltering by maintaining a database of Internet Protocol (IP) addresses and physical regions associated with such addresses. Another way to geofilter at the CDN level is to choose which Edge servers receive the stream, especially if the CDN s architecture is set up for routing by country or by lest-hop routing. Windows Media Microsoft refers to this with another set of terms more akin to server administration: authorization. In the case of Windows Media Services, authorization for access to protected resources includes content or media to which you want to control access, such as real-time content. Authorization works hand in hand with authentication, which confirms the user identity. In general, a user who fails authentication does not have permission to access the requested resource. Windows Media Services uses ACL checking to control privileges of a single Windows Media Player for access rights to any ASF, WMA, or WMV file, directory, or stream. This can be done at a file, directory, or drive partition level, but primarily if the drive partition is formatted as NTFS. Since unknown users cannot be authorized, ACL requires some form of authentication for every viewer, which makes it less likely to be used in geofiltering or georestriction, although Windows Media Services can use IP addresses to filter access. Flash By default, a client can connect to Flash Media Server from any domain or IP address, which can be a security risk. You can create a whitelist of allowed domains (or a blacklist of banned domains) to help ensure that only authorized clients can connect to your applications or services. You can add a comma-delimited list of domains and/or IP-address blocks in the configuration files to add this level of security, or use the Authorization plug-in. This is usually the first step in locking down your server; it prevents malicious or unauthorized domains from freely accessing your applications and streams. Key events When loading external media, listening for and reacting to events are a crucial part of any playback technology. One must be able to react to situations such as failed connections, degraded quality of service, file loading progress, and more to create a positive user experience. Windows Media Windows Media technologies can be triggered by JavaScript, Visual Basic, and procedural languages, but at its core, Windows Media uses the DirectShow API and its event notification codes. Microsoft has added a series of additional Windows Media event notification codes (the EC_ prefix having been removed from each): PLEASE_REOPEN A request to re-render a filter graph. STATUS Current status of stream. MARKER_HIT A marker (event trigger) has just been passed. LOADSTATUS Provides status of currently loading network file. FILE_CLOSED Event triggered when a file is involuntarily closed. 17

18 ERRORABORTEX An operation aborted because of error. EOS_SOON The source filter is about to deliver an End of Session (EOS). CONTENTPROPERTY_CHANGED A stream s description information changed. BANDWIDTHCHANGE A stream s bandwidth availability changed. VIDEOFRAMEREADY Initial video frame is about to be drawn. DRMSTATUS Triggered as various DRM process stages are reached. These events are certainly useful, but Flash offers a more comprehensive and granular set of events. Flash Flash Media Server scripting is essentially based on an event model. By listening for and reacting to these events, you can create applications that are flexible and robust. Some of the key media-related events in ActionScript include: NetConnection.netStatus Dispatched when a NetConnection is reporting its status or an error. The netstatus event contains an info property, which contains specific information about the event, such as whether a connection attempt succeeded or failed. NetStream.netStatus Invoked when a NetStream is reporting its status or an error. Contains the info property, which includes specific information about the event, such as whether a stream playback attempt succeeded or failed, buffer status, recording status, insufficient bandwidth errors, and so on. NetStream.onCuePoint Triggered when an embedded cue point is reached while playing a video file. NetStream.onMetaData Dispatched when Flash Player receives descriptive metadata embedded in the video being played. NetStream.onPlayStatus Invoked when a NetStream object has completely played a stream. VideoEvent.playheadTime Provides the current playhead time or position, measured in seconds, which can be a fractional value. VideoEvent.state Describes the playback state of the component (disconnected, stopped, playing, paused, buffering loading, connection error, rewinding, seeking). VideoProgressEvent.progress Provides the number of bytes loaded and the total number of bytes that will be loaded if the loading process succeeds. If you are using the prebuilt FLVPlayback component (in Flash CS4 Professional) to stream video in your application, these additional events will be broadcast: autolayout The video player has been resized or laid out automatically. autorewound The playhead has moved to the start of the video player because the autorewind property is set to true. bufferingstateentered The FLVPlayback instance entered the buffering state. close The event object closed the NetConnection. complete Playing is complete because the player reached the end of the video file. cuepoint A cue point has been reached. fastforward The location of the playhead moved forward by a call to the seek() method or by clicking the ForwardButton control. layout The video player has been resized or laid out. metadatareceived The video file s metadata has been read for the first time. pausedstateentered The player entered the paused state. playheadupdate Rewinding has started, or the video file is playing at the frequency specified by the playheadupdateinterval property. playingstateentered The playing state has been entered. 18

19 progress Progress made in number of bytes downloaded. ready A video file is loaded and ready to display. rewind The location of the playhead moved backward by a call to seek() or when an autorewind call was completed. scrubfinish The user stopped scrubbing the video file with the seek bar. scrubstart The user began scrubbing the video file with the seek bar. seeked The location of the playhead has changed by a call to seek() or by setting the playheadtime property or using the SeekBar control. skinerror An error occurred loading a skin SWF file. skinloaded A skin SWF file has been loaded. soundupdate Sound changed by the user by either moving the handle of the volumebar control or setting the volume or soundtransform property. statechange The playback state changed. stoppedstateentered Entered the stopped state. Dynamic Stream support (multibitrate auto shifting) Support for Live DVR (start at live, start at beginning) This is just a high-level overview of the media events in Flash; there are a wealth of additional methods and events you can use in your Flash Media Server applications, both client-side and server-side, and even communicating with external JavaScript. For more detail, refer to the ActionScript documentation or the Server-side Adobe ActionScript Language Reference for Adobe Flash Media Interactive Server. Large-scale deployments Servers have a finite capacity, so as traffic and throughput increases, applications need to be scaled to preserve quality of service. Windows Media Large-scale deployments typically use one of three approaches to scalability: multicast streaming at the server level, application layer multicasting, and proxy caching. Multicast Windows Media Services can provide application-layer multicasting, which could be used between servers on a CDN to minimize bandwidth requirements and then converted to a unicast for delivery from the Edge servers to the local end users. Two primary limitations of multicast involve router setup and limited security for multicast. Router setup is, perhaps, the biggest issue facing the adoption of multicast for video streaming, with the exception of the decision as to what gets multicast if overall bandwidth is limited. While a multicast IP session can handle multiple types of content including digital voice and video it relies upon random, less reliable packet-switched transmission. In real terms, this means that unlike a unicast, which may have difficulty being delivered to a few select clients, a multicast has the potential to create problems: There is no guarantee of packet sequence, jitter-free reception, data integrity, or packet arrival time. In fact, there s no guarantee that the packets will even arrive. Proper router setup, then, is an important step in multicasting, especially if routers have been set up with bandwidth- and latency-saving protocols such as Open Shortest Path First (OSPF). This type of uncertainty can cause problems ranging from minor, momentary interruptions of multicast video to serious disruptions that prevent the client application from displaying content. On the security side, multicasts aren t designed to limit viewership to a specific user or device. While encryption keys can be used to limit viewing of content, any machine on the network can receive the multicast content and store it for later decryption. According to a Microsoft Tech Note, selective content reception is not currently possible. 19

20 For all the reasons noted above, with the exception of transmission between CDN servers, multicasting is not yet a viable model for end-user delivery beyond the corporate LAN. Therefore, proxy caching has been more highly used. This proxy caching can be done either at the client side (the original model created by Burst Technologies and used in Windows Media Player 9 as Fast Start) or at the CDN or Windows Media servers. The latter model of caching at the server provides for authentication and access controls, but also has the downside of further delaying delivery beyond the typical buffering delay of a client-side caching, while not providing the smooth playback benefit that client-side caching provides. Flash Flash Media Server offers several approaches to load balancing in large-scale deployments: cluster deployment, Origin/Edge server configurations, and multipoint publishing. Cluster deployment allows you to deploy multiple servers behind a load balancer to distribute the application load evenly. Flash Media Server clustering enables you to scale an application to accommodate more clients reliably and creates redundancy, which eliminates single points of failure. This approach is generally best for live or video on demand (VOD) streaming, where clients do not need to communicate with each other from within specific application instances. Clustering can be achieved using either Adobe Flash Media Streaming Server or Flash Media Interactive Server software. Flash Media Interactive Server also provides an enterprise-ready Edge/Origin architecture designed to simplify load balancing, failover, and clustering to help ensure maximum availability over large regions. Figure 1 shows the Edge/Origin architecture. Figure 1. Flash Media Interactive Server can be deployed in an Origin-Edge configuration for virtually unlimited scalability. Edge/Origin server configurations improve performance by distributing the server load among many computers on a network. With an Edge/Origin deployment strategy, all connection requests from clients are redirected to an Edge server. The configuration also lets you maximize your network if you are supporting a large local network. By placing Edge servers in remote office locations, the Edge servers cache media files locally so each stream does not need to access the Origin (host) server for each stream. Caching static content further reduces the load on the Origin server. Typically Edge/Origin deployments are best used with one-way streaming services. 20